conv2d implementation

src/kernels/activation_elu.cu

@@ -1,5 +1,11 @@
 #include "kernels.h"
 
+/**
+    Exponential Linear Unit compute kernel
+    it does the following operation for each x input element:
+        x < 0 :    y = e^(x) -1
+        x > 0 :    y = x
+*/
 __global__
 void activation_elu(value_type *input, value_type *output, int size) {
 
@@ -7,9 +13,14 @@ void activation_elu(value_type *input, value_type *output, int size) {
     
     if(i<size) 
         output[i] =  (input[i]>0)*input[i] + (input[i]<0)*(expf(input[i]) -1);
+    
+    // the if x > or < is condensed in one operation for better threads flow 
  }
 
 
+/**
+    ELU activation function
+*/
 void activationELUForward(value_type* srcData, value_type* dstData, int size)
 {
     activation_elu<<<(size+255)/256, 256>>>(srcData, dstData, size);